Electronic expansion valve and manufacturing method

Abstract

The invention discloses an electronic expansion valve and a manufacturing method.The electronic expansion valve comprises a valve body and a coil component, the valve body comprises a valve seat, a valve element, a valve needle, a vertical connecting pipe and a transverse connecting pipe, the valve seat is provided with a first through hole and a second through hole, the valve element is welded and fixed to the second through hole, the valve element is provided with a third through hole, and the coil component is arranged in the third through hole. A valve port is formed in the upper end of the third through hole, the valve needle penetrates through the first through hole to be matched with the valve port, the valve seat, the valve element, the vertical connecting pipe and the transverse connecting pipe are made of copper, and the valve needle is made of stainless steel. A copper plating layer is arranged on the surface, used for being matched with the valve port, of the end of the valve needle, and the valve needle makes contact with the valve port through the copper plating layer in the full-closed state. The welding manufacturability and the sealing effect of the valve seat, the valve element and the connecting pipe and the economical efficiency of welding flux selection are improved, meanwhile, the valve port is not prone to being damaged due to extrusion of the valve needle, and the effect of improving the leakage performance of the valve body at low cost is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of valves, in particular to an electronic expansion valve. The present invention also relates to a manufacturing method of the electronic expansion valve. Background Art

[0002] The electronic expansion valve uses the electrical signal generated by the regulated parameter to control the voltage or current applied to the expansion valve, and further achieves the purpose of regulating the liquid supply amount. The stepless variable capacity refrigeration system has a wide regulation range of the refrigeration liquid supply amount and requires a fast regulation response. It is difficult for traditional throttling devices (such as thermal expansion valves) to perform well, while the electronic expansion valve can well meet the requirements.

[0003] In terms of the driving method, the electronic expansion valve can be generally divided into a direct-acting electronic expansion valve and a reduction-type electronic expansion valve. Taking the direct-acting electronic expansion valve as an example, it mainly consists of a valve seat component, a valve needle component, a nut, a rotor component, a stopper, etc. During operation, the coil is excited to drive the rotor component to rotate. The screw thread pair between the screw rod in the rotor component and the nut converts the rotational motion into the up-and-down motion of the valve needle component, and together with the valve port of the valve seat component, controls the refrigerant flow rate flowing through the valve port.

[0004] Due to the poor weldability of brass and stainless steel, the solder at the welded seal part of the electronic expansion valve is prone to uneven distribution and porosity, resulting in an increase in internal leakage of the valve body. Therefore, this structure has high requirements for the fluidity of the solder.

[0005] In addition, the valve seat is made of brass, and the valve seat and the valve port are of an integral structure, and the valve port part is also brass, with a relatively soft texture. It is not only easy to accumulate impurities, but also, in the fully closed state, is prone to being damaged by the relatively large pressure applied by the stainless steel valve needle. Summary of the Invention

[0006] The purpose of the present invention is to provide an electronic expansion valve to solve the above technical problems.

[0007] Another purpose of the present invention is to provide a manufacturing method of an electronic expansion valve.

[0008] To achieve the above purpose, the present invention provides an electronic expansion valve, including a valve body and a coil component. The valve body includes a valve seat, a valve core, a valve needle, a vertical connecting pipe, and a horizontal connecting pipe. A diversion cavity is provided inside the valve seat. A first through hole is provided in the upper part of the diversion cavity, and a second through hole is provided in the lower part of the diversion cavity. The valve core is welded and fixed to the second through hole. The valve core is provided with a third through hole, and the upper end of the third through hole forms a valve port. The valve needle passes through the first through hole and cooperates with the valve port. The valve seat, the valve core, the vertical connecting pipe, and the horizontal connecting pipe are made of copper, and the valve needle is made of stainless steel; the surface of the end of the valve needle for cooperating with the valve port is provided with a copper plating layer, and in the fully closed state, the valve needle contacts the valve port through the copper plating layer.

[0009] Optionally, the valve core includes an integrally formed first circular ring body and a second circular ring body. The outer diameter of the first circular ring body is greater than that of the second circular ring body, and the height of the second circular ring body is greater than that of the first circular ring body. The second through hole of the valve seat includes a large hole section and a small hole section, and a step surface is formed between the large hole section and the small hole section. The outer peripheral surface of the first circular ring body is connected to the inner wall of the large hole section by welding, the upper surface of the first circular ring body is connected to the step surface by welding, and the outer peripheral surface of the second circular ring body is connected to the inner wall of the small hole section by welding.

[0010] Optionally, the upper end of the valve core is provided with a first chamfer at the outer edge, and at least part of the area of the first chamfer is filled with the melted solder; the step surface is provided with a second chamfer at the inner edge, and the area of the second chamfer is filled with the melted solder; the upper surface of the first circular ring body is provided with a third chamfer at the outer edge, and the area of the third chamfer is filled with the melted solder; the insertion end of the vertical connecting pipe is provided with a fourth chamfer at the outer edge, and the area of the fourth chamfer is filled with the melted solder.

[0011] Optionally, the copper plating layer covers the outer surface of the valve needle.

[0012] Optionally, the copper plating layer covers the lower end or the sealing part of the valve needle.

[0013] Optionally, the surface of the end of the valve needle for cooperating with the valve port is a conical surface, and the copper plating layer covers the conical surface.

[0014] Optionally, the valve needle and the inner wall of the first through hole are in sliding fit in the axial direction to guide the valve needle.

[0015] Optionally, the thickness of the copper plating layer is 2μm - 3μm.

[0016] Optionally, the valve seat and the valve core are made of brass, and the vertical connecting pipe and the horizontal connecting pipe are made of red copper.

[0017] To achieve the above-mentioned another object, the present invention provides a method for manufacturing an electronic expansion valve, including the following steps:

[0018] Machining a first through hole, a second through hole and a diversion cavity on a valve seat made of copper;

[0019] Machining the valve core from a copper rod blank, and reserving machining allowance for fine boring of its third through hole during the machining process;

[0020] Machining a valve port at the upper end of the third through hole;

[0021] Installing the valve core into the valve seat so that the valve core and the valve seat cooperate with each other;

[0022] Insert the vertical connecting pipe and the horizontal connecting pipe made of copper into the valve seat, so that the insertion end of the vertical connecting pipe fits with the vertical interface of the valve seat, and the insertion end of the horizontal connecting pipe fits with the horizontal interface of the valve seat;

[0023] Perform tunnel furnace or flame brazing;

[0024] Precision boring the first through hole of the valve seat and the third through hole of the valve core coaxially;

[0025] Plating copper on the surface of the valve needle end for fitting with the valve port to form a copper coating;

[0026] Insert the valve needle made of stainless steel into the first through hole of the valve seat.

[0027] For the electronic expansion valve provided by the present invention, its valve seat, valve core, vertical connecting pipe, and horizontal connecting pipe are made of copper, and the valve needle is made of stainless steel. Since the materials of the valve seat, valve core, vertical connecting pipe, and horizontal connecting pipe are the same, according to the characteristic that the closer the materials are, the better the weldability is, the welding difficulty between the valve seat and the vertical connecting pipe and the horizontal connecting pipe can be reduced. In terms of solder selection, the silver content in the solder can be reduced or eliminated, thereby improving the welding economy between the valve seat and the vertical connecting pipe and the horizontal connecting pipe. In terms of welding effect, the solder filling of the entire welding surface is denser, reducing the risk of leakage and optimizing the sealing performance of the electronic expansion valve; moreover, the surface of the valve needle end for fitting with the valve port is provided with a copper coating, reducing the local hardness. In the fully closed state, the copper coating of the valve needle contacts the valve port made of the same copper material, making the valve port not easily damaged by the extrusion of the valve needle. Description of the Drawings

[0028] Figure 1 It is a schematic structural diagram of an electronic expansion valve provided by an embodiment of the present invention;

[0029] Figure 2 It is a schematic structural diagram of the valve needle cooperating with the valve core;

[0030] Figure 3 For Figure 2 Partial enlarged view;

[0031] Figure 4 It is a schematic structural diagram of the valve needle provided with a copper coating in the first way;

[0032] Figure 5 It is a schematic structural diagram of the valve needle provided with a copper coating in the second way;

[0033] Figure 6 It is a schematic structural diagram of the valve needle provided with a copper coating in the third way;

[0034] Figure 7 It is a schematic structural diagram of the valve needle provided with a copper coating in the fourth way;

[0035] Figure 8 This is a process flow diagram of a method for manufacturing an electronic expansion valve provided by an embodiment of the present invention.

[0036] In the figure:

[0037] 100. Valve body; 130. Valve seat; 131. First through hole; 132. Second through hole; 1321. Large hole section; 1322. Small hole section; 1323. Step surface; 140. Valve needle; 141. Copper plating; 150. Valve core; 151. First ring body; 152. Second ring body; 153. Third through hole; 160. Vertical connecting pipe; 170. Horizontal connecting pipe; 200. Coil component; 210. Excitation coil; 220. Nut; 230. Screw; 240. Rotor component; 250. And stopper; 260. Spring. Specific embodiments

[0038] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] In this article, terms such as "upper, lower, inner, outer" are established based on the positional relationship shown in the drawings. Depending on the different drawings, the corresponding positional relationship may also change accordingly. Therefore, it cannot be understood as an absolute limitation of the protection scope; moreover, relational terms such as "first" and "second" are only used to distinguish one component with the same name from another, and do not necessarily require or imply any such actual relationship or order between these components.

[0040] Please refer to Figure 1 , Figure 1 This is a structural schematic diagram of an electronic expansion valve provided by an embodiment of the present invention.

[0041] In a specific embodiment, the electronic expansion valve provided by the present invention is a direct-acting electronic expansion valve, which can be widely applied to refrigeration and heating devices or equipment such as air conditioners, heat pump water heaters, chillers, vending machines, ice makers, supermarket freezers, and refrigerators.

[0042] This direct-acting electronic expansion valve mainly consists of two major parts: a valve body 100 and a coil component 200. The valve body 100 is used to regulate the flow rate, and the coil component 200 is used to drive the valve body 100 to perform the action of regulating the flow rate. Among them, the valve body 100 has core components such as a valve seat 130, a valve needle 140, a vertical connecting pipe 160, and a horizontal connecting pipe 170. The coil component 200 has an excitation coil 210, a nut 220, a screw 230, a rotor component 240, and a stopper 250, etc.

[0043] During operation, the exciting coil 210 is electrically connected to the control circuit. When energized, the exciting coil 210 drives the rotor component 240 to rotate, and further drives the valve needle 140 to act through the screw transmission mechanism. When the rotor component 240 rotates, due to the action of the thread structure, the screw 230 rotates and moves up and down relative to the nut 220 driven by the rotor component 240. Since the valve needle 140 is relatively fixed to the screw 230, the valve needle 140 moves up and down with the screw 230.

[0044] A spring 260 is provided between the valve needle 140 and the screw 230. In the axial and radial directions, there can be a certain relative displacement between the valve needle 140 and the screw 230 to play an elastic buffering role.

[0045] Please continue to refer to Figure 2 、 Figure 3 、 Figure 4 , Figure 2 which is a schematic structural diagram of the cooperation between the valve needle and the valve core; Figure 3 is Figure 2 a partial enlarged view of Figure 4 which is a schematic structural diagram of the valve needle provided with a copper plating layer in the first way.

[0046] The valve seat 130 is made of brass. A diversion cavity is provided inside it. A first through hole 131 is provided at the upper part of the diversion cavity, and a second through hole 132 is provided at the lower part of the diversion cavity. The first through hole 131 and the second through hole 132 are on the same axis. The vertical connecting pipe 160 and the horizontal connecting pipe 170 can both be made of red copper. The upper end of the vertical connecting pipe 160 is inserted into the second through hole 132 of the valve seat 130 and is welded to both the valve seat 130 and the valve core 150. One end of the horizontal connecting pipe 170 is inserted into the side opening of the valve seat 130 and is welded to the valve seat 130.

[0047] The valve core 150 is also made of brass. It is fixed in the second through hole 132 of the valve seat 130. A third through hole 153 is provided on the valve core 150. The upper end of the third through hole 153 forms a valve port. A machining allowance for finish boring is reserved for the third through hole 153 so that after welding is completed, it can be finish bored coaxially with the first through hole 131.

[0048] The valve needle 140 is made of stainless steel. It passes through the first through hole 131 from top to bottom and is in sliding fit with the inner wall of the first through hole 131 in the axial direction to guide the valve needle 140. The valve needle 140 realizes the flow regulation function by cooperating with the valve port.

[0049] When the valve needle 140 moves downward, the valve port gradually decreases until it is fully closed. When the valve needle 140 moves upward, the valve port component increases until it is fully open.

[0050] The surface of the end of the valve needle 140 for mating with the valve port is provided with a copper plating layer 141. In the fully closed state, the valve needle 140 contacts the valve port through the copper plating layer 141.

[0051] In this embodiment, the copper plating layer 141 covers the entire outer peripheral surface of the valve needle 140, and the thickness is 2μm - 3μm.

[0052] The sealing part of the valve needle 140 is provided with an outer conical surface, and the pressure-bearing part of the valve port is provided with a corresponding inner conical surface. In the fully closed state, the outer conical surface of the valve needle 140 fits with the inner conical surface of the valve port through the copper plating layer 141.

[0053] Specifically, the valve core 150 has an integrally formed first annular body 151 and a second annular body 152. The outer diameter of the first annular body 151 is larger than that of the second annular body 152, and the height of the second annular body 152 is greater than that of the first annular body 151. The second through hole 132 of the valve seat 130 includes a large hole section 1321 and a small hole section 1322, and a step surface 1323 is formed between the large hole section 1321 and the small hole section 1322. The outer peripheral surface of the first annular body 151 is welded to the inner wall of the large hole section 1321, the upper surface of the first annular body 151 is welded to the step surface 1323, and the outer peripheral surface of the second annular body 152 is welded to the inner wall of the small hole section 1322.

[0054] The upper end of the valve core 150 is provided with a first chamfer a at the outer edge, and at least part of the area of the first chamfer a is filled with the melted solder; the step surface 1323 is provided with a second chamfer b at the inner edge, and the area of the second chamfer b is filled with the melted solder; the upper surface of the first annular body 151 is provided with a third chamfer c at the outer edge, and the area from the third chamfer c is filled with the melted solder; the insertion end of the vertical pipe 160 is provided with a fourth chamfer d at the outer edge, and the area of the fourth chamfer d is filled with the melted solder.

[0055] The copper plating of the valve needle 140 can be carried out by electroplating or electroless plating, etc. Before copper plating, surface treatment of the steel body needs to be carried out, including removing oil stains and oxide scales, etc. After the valve seat 130, the valve core 150, the vertical pipe 160, and the horizontal pipe 170 are assembled, tunnel furnace or flame brazing is carried out.

[0056] Since the seat 130, the valve core 150, the vertical pipe 160, and the horizontal pipe 170 are made of the same material, according to the characteristic that the closer the materials are, the better the weldability is, the welding difficulty between the seat 130 and the vertical pipe 160 and the horizontal pipe 170, as well as the welding difficulty between the seat 130 and the valve core 150 can be reduced. In terms of solder selection, solder with a reduced or eliminated silver content in the solder can be used, thereby improving welding economy. In terms of welding effect, the solder filling of the entire welding surface is made denser, reducing the risk of leakage and optimizing the sealing performance of the electronic expansion valve. Moreover, a copper plating 141 is provided on the surface of the end of the valve needle 140 for mating with the valve port, reducing the local hardness of the valve needle 140. In the fully closed state, the copper plating 141 of the valve needle 140 contacts the valve port made of the same copper material, making it less likely for the valve port to be damaged by the extrusion of the valve needle 140.

[0057] In addition, after the welding of the seat 130 component is completed, the first through hole 131 of the seat 130 and the third through hole 153 of the valve core 150 can be finish-bored to ensure the coaxiality between the valve needle guiding section and the valve port, improving the product's operating performance.

[0058] Furthermore, by designing the first chamfer a, the second chamfer b, the third chamfer c, and the fourth chamfer d, a cavity for accommodating the solder can be formed. During the welding process, the capillary action is increased, improving the solder fluidity. After the welding is formed, more solder accumulates at the position of the cavity, providing four welding anchoring points. Moreover, the solder in the cavity is in a ring shape, equivalent to providing four circumferential sealing parts with local strengthening. Compared with a solder layer of a single thickness, a more stable and reliable welding effect and sealing effect can be obtained.

[0059] The above embodiments are only the preferred solutions of the present invention, and are not specifically limited thereto. On this basis, targeted adjustments can be made according to actual needs to obtain different implementation manners. For example, the copper plating 141 can only cover the lower end of the valve needle 140 (see Figure 5 ), or the copper plating 141 can only cover the sealing part of the valve needle 140 and the upper and lower edges of the sealing part (see Figure 6 ), or the copper plating 141 can only cover the sealing part of the valve needle 140 and the sealing part (see Figure 7 ), etc. Since there are many possible implementation manners, they will not be listed one by one here.

[0060] Please refer to Figure 8 , Figure 8 which is the process flow chart of a method for manufacturing an electronic expansion valve provided by an embodiment of the present invention.

[0061] In addition to the above electronic expansion valve, the present invention also provides a method for manufacturing an electronic expansion valve for processing and manufacturing the electronic expansion valve described above, including the following steps:

[0062] S01: Machine a first through-hole 131, a second through-hole 132, and a diversion cavity on the valve seat 130;

[0063] S02: Machine the valve core 150 from a copper rod stock, and reserve machining allowance for finish boring the third through-hole 153 during the machining process;

[0064] S03: Machine a valve port at the upper end of the third through-hole 153;

[0065] S04: Install the valve core 150 into the valve seat 130 so that the valve core 150 cooperates with the valve seat 130;

[0066] S05: Install the vertical connecting pipe 160 made of copper and the horizontal connecting pipe 170 made of copper into the valve seat 130, so that the insertion end of the vertical connecting pipe 160 cooperates with the vertical interface of the valve seat 130, and the insertion end of the horizontal connecting pipe 170 cooperates with the horizontal interface of the valve seat 130;

[0067] S06: Perform tunnel furnace or flame brazing on the assembled parts;

[0068] S07: Perform coaxial finish boring on the first through-hole 131 of the valve seat 130 and the third through-hole 153 of the valve core 150. Through finish boring, the coaxiality between the valve needle guiding section and the valve port can be ensured, and the product operation performance can be improved;

[0069] S08: Plate the surface of the end of the valve needle 140 made of stainless steel that is used to cooperate with the valve port with copper to form a copper plating layer 141;

[0070] S09: Install the valve needle 140 into the first through-hole 131 of the valve seat 130.

[0071] By adopting a valve seat 130, a valve core 150, a vertical connecting pipe 160, a horizontal connecting pipe 170 made of copper, and a valve needle 140 made of stainless steel, and providing a copper plating layer 141 on the surface of the end of the valve needle 140 that is used to cooperate with the valve port, the present invention improves the welding processability, sealing effect, and economy of solder selection between the valve seat 130 and the valve core 150, the vertical connecting pipe 160, and the horizontal connecting pipe 170. At the same time, the valve port is not easily damaged by the extrusion of the valve needle 140, achieving the effect of improving the leakage performance of the valve body at low cost.

[0072] The above has introduced the electronic expansion valve and manufacturing method provided by the present invention in detail. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the core idea of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. Electronic expansion valve, comprising a valve body (100) and a coil component (200), characterized in that, The valve body (100) includes a valve seat (130), a valve core (150), a valve needle (140), a vertical connecting pipe (160), and a horizontal connecting pipe (170). A diversion cavity is provided inside the valve seat (130). A first through hole (131) is provided in the upper part of the diversion cavity, and a second through hole (132) is provided in the lower part of the diversion cavity. The valve core is fixedly welded to the second through hole (132). The valve core (150) is provided with a third through hole (153), and the upper end of the third through hole (153) forms a valve port. The valve needle (140) passes through the first through hole (131) and cooperates with the valve port. The valve seat (130), the valve core (150), the vertical connecting pipe (160), and the horizontal connecting pipe (170) are made of copper, and the valve needle (140) is made of stainless steel. The surface of the end of the valve needle (140) for cooperating with the valve port is provided with a copper coating (141). In the fully closed state, the valve needle (140) contacts the valve port through the copper coating (141).

2. The electronic expansion valve according to claim 1, characterized in that, The valve core (150) includes an integrally formed first ring body (151) and a second ring body (152). The outer diameter of the first ring body (151) is larger than the outer diameter of the second ring body (152), and the height of the second ring body (152) is greater than the height of the first ring body (151). The second through hole (132) of the valve seat (130) includes a large hole section (1321) and a small hole section (1322), and a step surface (1323) is formed between the large hole section (1321) and the small hole section (1322). The outer peripheral surface of the first ring body (151) is welded to the inner wall of the large hole section (1321), the upper surface of the first ring body (151) is welded to the step surface (1323), and the outer peripheral surface of the second ring body (152) is welded to the inner wall of the small hole section (1322).

3. The electronic expansion valve according to claim 2, wherein The upper end of the valve core (150) is provided with a first chamfer (a) at the outer edge, and at least part of the area of the first chamfer (a) is filled with melted solder. The step surface (1323) is provided with a second chamfer (b) at the inner edge, and the area of the second chamfer (b) is filled with melted solder. The upper surface of the first ring body (151) is provided with a third chamfer (c) at the outer edge, and the area of the third chamfer (c) is filled with melted solder. The insertion end of the vertical connecting pipe (160) is provided with a fourth chamfer (d) at the outer edge, and the area of the fourth chamfer (d) is filled with melted solder.

4. The electronic expansion valve according to claim 3, wherein The copper coating (141) covers the outer surface of the valve needle (140).

5. The electronic expansion valve according to claim 3, characterized in that, The copper coating (0141) covers the lower end or the sealing part of the valve needle (140).

6. The electronic expansion valve according to claim 5, characterized in that, The surface of the end of the valve needle (140) for cooperating with the valve port is a conical surface, and the copper coating (141) covers the conical surface.

7. The electronic expansion valve according to claim 3, wherein The valve needle (140) and the inner wall of the first through hole (131) are in sliding fit in the axial direction to guide the valve needle (140).

8. The electronic expansion valve according to any one of claims 1 to 7, characterized in that, The thickness of the copper coating (141) is 2μm - 3μm.

9. The electronic expansion valve according to any one of claims 1 to 7, characterized in that, The valve seat (130) and the valve core (150) are made of brass, and the vertical connecting pipe (160) and the horizontal connecting pipe (170) are made of red copper.

10. A method for manufacturing an electronic expansion valve, comprising the following steps: Machining a first through hole (131), a second through hole (132) and a diversion cavity on a valve seat (130) made of copper; Machining the valve core (150) from a copper rod stock, and reserving machining allowance for finish boring the third through hole (153) during the machining process; Machining a valve port at the upper end of the third through hole (153); Installing the valve core (150) into the valve seat (130) so that the valve core (150) cooperates with the valve seat (130); Installing the vertical connecting pipe (160) made of copper and the horizontal connecting pipe (170) made of copper into the valve seat (130), so that the insertion end of the vertical connecting pipe (160) cooperates with the vertical interface of the valve seat (130), and the insertion end of the horizontal connecting pipe (170) cooperates with the horizontal interface of the valve seat (130); Performing tunnel furnace brazing or flame brazing; Performing coaxial finish boring on the first through hole (131) of the valve seat (130) and the third through hole (153) of the valve core (150); Plating copper on the surface of the end of the valve needle (140) made of stainless steel for cooperating with the valve port to form a copper coating (141); Inserting the valve needle (140) into the first through hole (131) of the valve seat (130).

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